That's an important question, Jim. A receive preamp is one of my favorite topics and one of the top 10 questions I'm asked by hams, regardless of whether it is for low band RX antennas or in the VHF and above region. The question is "Do I need a preamp?" to which I always respond "I don't know, do you?". Its not meant to be a snooty response but a valiant effort to get the person to study and learn about preamps and what one does in an antenna system or circuit. The person can then determine why they do, or do not, need one and assess what is right for their situation. The one wavelength Beverages used at my station have sufficient gain, and adequate SNR that I don't believe one is necessary.
As I noted in the paper, geographical areas differ and there are RX antenna designs that benefit from a preamp, but not all of them in all situations. 73 Joel W5ZN -----Original Message----- From: Topband <[email protected]> On Behalf Of Jim Brown Sent: Tuesday, January 14, 2025 2:58 PM To: [email protected] Subject: Re: Topband: Comparison of Vertical Arrays for Low Band Receiving On 1/14/2025 12:13 PM, [email protected] wrote: > Thanks. No, I did not have preamps at the feed point of the Beverages. Is the sensitivity of a one wavelength Beverage low enough that a preamp at the feedpoint is needed? Loss in decent coax is pretty low at 2 MHz, and where I live, electronic noise has gotten high enough that I can't imagine it being a limitation. My reversible one wavelength Beverages (one EU-VK, the other SA-JA) point to noisy homes facing EU and JA, so they've become next to useless. My 8 acres are in a dense redwood forest, with terrain that varies by at least 50 ft in elevation, so any of these vertical arrays are out of the question. I am finding some benefit from an array of two VE3DO loops spaced 5/8 wave, but one of them is quite close to the noisy EU home, and points at it. :) I'm phasing it with an NCC-1, which allows me to shift the pattern between northern EU and New England. 73, Jim K9YC _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
